Mapping with sf

dc_loc <- geocode("Washington, D.C.")

## Source : https://maps.googleapis.com/maps/api/geocode/json?address=Washington,+D.C.&key=xxx-EvQ

dc_map <- qmap(c(lon=dc_loc$lon, lat=dc_loc$lat), source="google", zoom=12)

## Source : https://maps.googleapis.com/maps/api/staticmap?center=38.907192,-77.036871&zoom=12&size=640x640&scale=2&maptype=terrain&language=en-EN&key=xxx-EvQ

dc_map

ph_loc <- geocode("Philadelphia")

## Source : https://maps.googleapis.com/maps/api/geocode/json?address=Philadelphia&key=xxx-EvQ

ph_map <- qmap(c(lon=ph_loc$lon, lat=ph_loc$lat), source="google", zoom=12)

## Source : https://maps.googleapis.com/maps/api/staticmap?center=39.952584,-75.165222&zoom=12&size=640x640&scale=2&maptype=terrain&language=en-EN&key=xxx-EvQ

ph_map

ny_loc <- geocode("New York")

## Source : https://maps.googleapis.com/maps/api/geocode/json?address=New+York&key=xxx-EvQ

ny_map <- qmap(c(lon=ny_loc$lon, lat=ny_loc$lat), source="google", zoom=12)

## Source : https://maps.googleapis.com/maps/api/staticmap?center=40.712775,-74.005973&zoom=12&size=640x640&scale=2&maptype=terrain&language=en-EN&key=xxx-EvQ

ny_map

# lv_loc <- geocode("Clark County, N.V.")
# lv_map <- qmap(c(lon=lv_loc$lon, lat=lv_loc$lat), source="google", zoom=12)
# lv_map

world <- ne_countries(scale = "medium", returnclass = "sf")
class(world)

## [1] "sf"         "data.frame"

ggplot(data = world) +
    geom_sf(color = "black", fill = "lightgreen") +
    xlab("Longitude") + ylab("Latitude") +
    ggtitle("World map", subtitle = paste0("(", length(unique(world$NAME)), " countries)"))

ggplot(data = world) +
    geom_sf(aes(fill = pop_est)) +
    scale_fill_viridis_c(option = "plasma", trans = "sqrt")

ggplot(data = world) +
    geom_sf() +
    annotation_scale(location = "bl", width_hint = 0.5) +
    annotation_north_arrow(location = "bl", which_north = "true", 
        pad_x = unit(0.75, "in"), pad_y = unit(0.5, "in"),
        style = north_arrow_fancy_orienteering) +
    coord_sf(xlim = c(-102.15, -74.12), ylim = c(7.65, 33.97), expand = FALSE)

## Scale on map varies by more than 10%, scale bar may be inaccurate